1. Field of the Invention
This invention relates to a semiconductor device with an internal power supply circuit, together with a liquid crystal device and electronic equipment that use the same, and, in particular, to the prevention of erroneous operation in the event of a power supply emergency, such as when a battery is removed.
2. Description of Related Art
In a liquid crystal display device, voltages are applied to a liquid crystal that is sandwiched between substrates on which electrodes are formed, to provide a display. This type of liquid crystal display device has recently become common in various types of electronic equipment, such as personal computers, word processors, portable telephones, and electronic organizers.
Electronic equipment that has such a liquid crystal display device has countermeasures such that the screen is momentarily blanked when power is turned off in a predetermined sequence. However, a phenomenon called momentary lighting can occur if the display is ended in a different sequence such as the battery is removed abruptly when the display is being driven or the electronic equipment is forcibly terminated. This phenomenon causes a momentary blanking of the screen when the battery is removed while the display is being driven, followed by the display artifacts such as horizontal lines on the screen for a while, by way of example.
The present inventors have analyzed the causes of this momentary lighting phenomenon and have devised this invention in the light thereof.